A low thermal shrinkage and high modulus fiber is desired in belts or carcasses of radial tires but may cause some problems in bias type tire constructions. A small amount of shrinkage is necessary to no-reset performance in V-belts and prevents "wavy fabric" under belts of radial carcasses. Reasonable modulus gives more flexibility in tire building and gives better load distribution and better fatigue resistance in bias tires. Combining two different types of yarn in forming a tire cord has been shown in previous work to give properties between those of similar cords made from the individual fibers, for example, F. J. Kovak et al. "Merged Fibers: Tailored Textiles for Tires" presented at the 1965 Spring meeting of the American Chemical Society Rubber Division in Miami Beach, Fla.